The present invention relates to a method of generating a metal vapor in a metal vapor laser by means of another laser.
A prior art metal vapor laser shown in FIG. 3 comprises a laser discharge tube 1 having sealed therein a buffer gas such as helium. Within the discharge tube 1, a solid piece of metal 5 located in a metal reservoir 3 is heated, melted and vaporized by a heating element 9 of a heater 7. A sufficiently high voltage is applied a heater 7. A sufficiently high voltage is applied between a pair of electrodes 15 and 17 provided on both sides of the metal reservoir 3 within the tube 1, whereby electric discharge occurs which will excite the thus vaporized metal atoms. The thus excited metal atoms will give off energy in the form of light or photons by a process of chain stimulated emission. A beam of the thus generated coherent photons is increasingly intensified while being repeatedly reflected by concave mirrors 19 and 21 provided outside the tube 1 at both ends thereof facing toward each other. An output metal vapor laser beam will emerge from one of the concave mirrors 21.
There are the following problems with such a prior art laser:
(a) Since the metal reservoir, the metal piece in it, and the heater have a relatively large heat capacity, it takes a relatively long time to vaporize the metal by heating it.
(b) For the same reason, the response is relatively slow when the temperature of the metal piece should be changed to adjust the density of the metal vapor.
(c) Where a metal is vaporized which has a melting point of higher than about 1300.degree. C. and is difficult to vaporize, there is a problem of the heat resistance of some elements, such as the metal reservoir and the discharge tube. Thus, it is difficult to produce metal vapor lasers in which metals of high melting points are to be used as the oscillating medium.